Russia's President Vladimir Putin (right) exchanges documents with Xi Jinping during a signing ceremony at the Kremlin in Moscow. Photo: Reuters

Chinese leader Xi Jinping's three-day visit to Russia was his first state visit after assuming the presidency on March 14.

In the Kremlin, Xi and Russian President Vladimir Putin signed a joint declaration, vowing to extend economic co-operation and steadfastly buttress each other in regional and global affairs.

The venue as well as the drastically deepened ties between the two former allies, especially their security implications, struck a responsive chord in world media.

Xi's predecessor Hu Jintao also made Moscow his first foreign stop after becoming president in 2003.

In fact, since 2000, the two sides have realised reciprocal state visits every other year.

But a comparison with mutual statements made over the past decade reveals unprecedented wording in the new joint declaration, which attest to the determination of the two countries to forge a much closer relationship.

The communiqué states: "Both sides will make developing the comprehensive strategic partnership of

co-operation with the other side a priority in its foreign policy orientation," and "resolutely back each other's core interests in protect sovereignty, territorial integrity and security".

The joint declaration of 2010 and 2011 made vague references to Sino-Russian ire over US missile defence systems. But this year, Xi and Putin explicitly admonished the US without naming it. "China and Russian are opposed to any unilateral and unrestrained building of anti-missile capabilities by a single country or a group of countries," the document proclaimed, "as such moves jeopardise strategic stability and international security."

Apparently, Xi taking Russia as his first foreign destination reflects Beijing's deep security worries, with the situation on the Korean Peninsula topping the list. Pyongyang's recent nuclear test and subsequent provocations plunged the peninsula into an abyss of uncertainty, posing unparalleled security threats to China.

Even if the current crisis could develop into a peaceful resolution, the Korean Peninsula has undisputedly entered a period of continuous and unpredictable turbulence. Beijing has to get a Russian nod on its possible moves to protect Chinese interests in North Korea in the worst-case scenario.

China's territorial disputes with Japan are assuredly high on Xi's mind. Amid the dragged-on confrontation over the contested Diaoyu Islands (Senkaku in Japanese), the United States and Japan last month discussed contingency military plans to defend Tokyo's claims.

Along with South Korea, Japan will host the US' anti-missile systems in Asia. Consequently, China wants to rally support from Russia, which is also at odds with Japan over territories.

Above all, Beijing needs Moscow's help to counterbalance the US pivot, or rebalancing, towards Asia.

But neither China nor Russia will really align with the other party. Russian tsar Alexander III once said that "Russia has only two reliable allies - the army and the navy". Currently, Russia has its own agenda in the Asia-Pacific region. Early last month, Russian Defence Minister Shoigu, the same general who hosted Xi, visited Vietnam, China's major rival in the jousting match over South China Sea territory. He announced the two had become "comprehensive strategic partners", selling Hanoi advanced submarines and fighter jets.

Meanwhile, Japanese Prime Minister Shinzo Abe is slated to visit Russia later this month.

In the global arena, China also has two reliable allies: trade and foreign currency reserve. China-Russia trade turnover was US$87.5 billion last year and is projected to be US$200 billion in 2020. Trade with the US reached about US$500 billion in 2012.

Improving ties with Russia will enable China more flexibility in dealing with various diplomatic challenges, but wooing Moscow hasn't led to Beijing snubbing Washington. After Xi was installed as president, the first foreign guest he received was US Treasury Secretary Jack Lew, and China is to participate in US naval exercises next year.

Presently, there are signs that China wants to ratchet down tensions with Japan. If the US can seize the opportunity to play a leading role in pacifying the waters in the Asia-Pacific, maintaining regional stability is not an impossible task.

Today, it is unwise to understand relations between China, Russia and the United States by simply applying Machiavellian calculations, and how to promote mutual or multilateral understanding to avoid feuding among the great powers is clearly a daunting challenge for the big three.